Supercritical solvents such as supercritical water (SCW) and supercritical carbon dioxide (SCCO2) have been used in extracting various substances and assisting chemical reactions. For example, U.S. Pat. No. 5,516,952 presents a process for breaking down natural, synthetic, vulcanized, and non-vulcanized rubbers. U.S. Pat. No. 5,830,763 describes a process for the preparation of organic and inorganic deuterium-tagged compounds by heating with deuterium oxide under supercritical conditions. U.S. Pat. No. 6,180,845 describes a process for the fractionation of waste biomass into a hydrocarbon mixture. U.S. Pat. Nos. 4,543,190 and 4,338,199 describe processes for the oxidation of organic compounds in supercritical water.
D. Boocock et al., “Liquefaction of biomass by rapid hydrolysis” Can. J. Chem. Eng., 61:80 (1983) discloses the use of supercritical water to liquefy biomass. Peter et al., “High pressure extraction of lignin from biomass” Supercritical fluid technology, p. 385 (1985) discloses the use of supercritical fluids to extract lignin from biomass. Houghton et al., “Reactivity of some organic compounds with supercritical water” Fuel, 61:827 (1986) discloses the use of supercritical fluids to decompose some organic compounds. Modell et al., “Supercritical water oxidation of pulp mill sludges” TAPPI J., 75:195 (1992) discusses the use of supercritical water for the oxidation of pulp mill sludges. B. Potic et al., “Gasification of Biomass model compound and real biomass in Supercritical Water,” Biomass and Bioenergy, 26:71-78 (2004); F. C. Knopf et al., “Reactive Extraction of Lignin from biomass using supercritical ammonia-water mixtures” J. Supercritical Fluids, 6:249-254 (1993); B. J. McCoy et al., “Extraction of Lignin from biomass with supercritical alcohol” J. Supercritical Fluids, 2:80-84 (1989); and B. Bennett et al., “Chemicals from forest products by supercritical fluid extraction” Fluid Phase Equil., 10:337 (1983) also provide further background information on use of supercritical fluids.
Methods for efficiently converting biomass from renewable resources or waste materials to more valuable products are desirable.